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# Fan speed rev/sec?

An electric fan is running on HIGH. After fan has been running for 1.1 minutes, the LOW button is pushed. The fan slows down to 85 rad/sec in 1.85 seconds. The blades of the fan have a diameter of 6.7 meters and their deceleration rate is 4.9 rad/sec2.

1)What was the initial angular speed of the fan in rev/sec?

ωi =

### 1 Answer

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- NCSLv 71 month agoFavourite answer
ω = ω₀ + αt

85 rad/s = ω₀ - 4.9rad/s² * 1.85s

ω₀ = 94 rad/s = 15 rev/s

(after dividing by 2π)

Hope this helps!

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